Patent GB-765014-A (GB)
Title: Improvements in or relating to toasting apparatus
Inventor: PARR BERNARD FRANKLIN
IPC: A47J37/08
Filed: 1955-02-23
Abstract: 765,014. Automatic electric toasters. WESTINGHOUSE ELECTRIC INTERNATIONAL CO. Feb. 23, 1955, No. 5377/55. Class 28(1) [Also in Group XXXVII] A toaster comprises means for moving the bread carriage from its toasting to its non-toasting position and timing means including a member which is rotated slowly through a first range of movement and more quickly through a second range of movement the ratio of the periods of time spent in each movement being adjustable and means actuated by said member towards the conclusion of the second range of movement for operating the carriage moving means. The toaster has a base 10 and a casing 11 with partitions 12, 13 dividing it into a compartment 15, and an oven 14 into which slice bars 16 extend through slots in partition 13 from compartment 15 where they are secured to a carriage 21 slidably supported on vertical guide rods 22. Heating elements 17 with guard wires 18 are provided in oven 14. A thermostatically operated switch 23 is connected in series with elements 17 and operates to energize and de-energize the heater elements in response to the temperature thereof during toasting. A motor driven mechanism 25 for lowering and raising carriage 21 and timing the toasting comprises frames 26, 27 secured to a plate 28 integral with partition 13. A substantially constant speed motor 29 supported by frame 27 drives a gear train 31 including a relatively high speed gear 32 and a relatively low speed gear 33. Gear 32 is fixed to shaft 34 and rotates it at approximately 30 revolutions per minute within a hollow shaft 35 carrying gear 33 which is rotated at approximately 1 revolution in 2¢ minutes. Shafts 35, 34 are journalled respectively in frames 27, 26. A segmental gear 36 is journaled on shaft 34 and may be driven by either shaft 35 or shaft 34 through pawl and ratchet clutches 37, 38 respectively. Clutch 37 includes a rotary ratchet wheel 39 fixed to shaft 35 and engaging a pawl 41 carried by a pin 42 secured to segment 36 and biased into engagement with wheel 39 by spring 43 so that segment 36 will be driven slowly. Clutch 38 includes a ratchet wheel 45 fixed to shaft 34 and engaged by a pawl 46 carried on an extension of pin 42 and either biased into or out of engagement with ratchet wheel 45 by an over-centre compression spring 47 carried by pin 48 and engaging notch 49 in pawl 46. When segment 36 is driven by pawl 46, pawl 41 slides over ratchet 39 as the latter rotates. Clutch 38 is engaged when pawl 46 is rotated about pin 42 and spring 47 is moved over-centre, this rotation being caused by the engagement of a projection 52 on pawl 46 with an adjustable stop 53 controlled by knob 86. Clutch 38 is disengaged when a second projection 54 on pawl 46 engages a fixed stop 55 and pushes pawl 46 round until spring 48 has moved overcentre. Stops 53, 55 are sufficiently flexible to allow projections 52, 54 to pass after spring 47 has been moved over-centre. Segment 36 has an arcuate series of gear teeth 58 which, during part of its rotation, engage with the teeth of a pinion 59 fixed to a shaft 61 journalled in frames 26, 27 and carrying a crank arm 62 at its inner end. A crank pin 63 connects arm 62 to a connecting rod 64 whose upper end is connected through a swivel pin 65 to an ear 66 projecting downwardly from a flange 67 on carriage 21. Operation of the toaster is initiated by pressing a spring biased plunger 81 to close contacts 72, 74 which are biased towards one another but are held apart by a flange 67 on the toasting carriage which engages a pin 75 secured to the strip carrying contact 74. Closing of contacts 72, 74 starts motor 29 and when gear 36 has rotated sufficiently to move the overcentre linkage supporting the toasting carriage anticlockwise in Fig. 1 so that the carriage descends under gravity. Plunger 81 may now be released as contacts 72, 74 will remain closed. After the operation has been timed the gear teeth will again engage pinion 59 to turn the over-centre linkage so as to raise the carriage to the non-toasting position where it engagaes pin 75 to open switch 71. The carriage 21 may be raised at any time by rotating a handle 95 which starts high speed rotation of gear 36 and subsequent termination of toasting.